【正文】 ion to posi tive direction because of the location of the gate, par ticularly the 9 greatest change of the fiber orientation appears near the gate. The great diversification of fiber orientation caused by gate location introduces serious differential shrinkage. Accordingly, the fea ture warpage is notable and the gate location must be optimized to reduce part warpage To optimize the gate location, the simulated an nealing searching discussed in the section “Simulated annealing algorithm” is applied to this part. The maximum number of iterations is chosen as 30 to ensure the precision of the optimization, and the maximum number of random trials allowed for each iteration is chosen as 10 to decrease the probability of null iteration without an iterative solution. Node N7379 () is found to be the optimum gate lo ca tion. 10 The feature warpage is evaluated from the war page simulation results f(X)=γ=%, which is less than that of the remended gate by MPI. And the part warpage meets the manufacturer’s requirements in trial manufacturing. shows the fiber orien tation in the simulation. It is seen that the optimal gate location results in the even glass fiber orie ntation, and thus introduces great reduction of shrinkage differ ence on the vertical direction along the longitudinal direction. Accordingly, the feature warpage is re duced. CONCLUSION Feature warpage is defined to describe the war page of injection molded parts and is evaluated based on the numerical simulation software MPI in this investigation. The feature warpage evaluation based on numerical simulation is bined with simulated annealing algorithm to optimize the single gate loca tion for plastic injection mold. An industrial part is taken as an example to illustrate the proposed method. The method results in an optimal gate location, by which the part is satisfactory for the manufacturer. This method is also suitable to other optimization problems for warpage minimization, such as location optimization for mult iple gates, runner system bal ancing, and option of anisotropic materials. 11 注塑模的單澆口優(yōu)化 摘要： 本文論述了一種單澆口位置優(yōu)化注塑模具 的 方法 。 p is the injection pressure at the gate position。 A and B are the terminal nodes of the feature to projectingdirection ()。j, and WzSingle gate optimization for plastic injection mold Abstract: Abstract: This paper deals with a methodology for single gate location optimization for plastic injection mold. The objective of the gate optimization is to minimize the warpage of injection molded parts, because warpage is a crucial quality issue for most injection molded parts while it is influenced greatly by the gate location. Feature warpage is defined as the ratio of maximum displacement on the feature surface to the projected length of the feature surface to describe part warpage. The optimization is bined with the numerical simulation technology to find the optimal gate location, in which the simulated annealing algorithm is used to search for the optimum. Finally, an example is discussed in the paper and it can be concluded that the proposed method is effective. Key words: Injection mold, Gate location, Optimization, Feature warpage. INTRODUCTION Plastic injection molding is a widely used, plex but highly efficient technique for producing a large variety of plastic products, particularly those with high production requirement, tight tolerance, and plex shapes. The quality of injection molded parts is a function of plastic material, part geometry, mold structure and process conditions. The most important part of an injection mold basically is the following three sets of ponents: cavities, gates and runners, and cooling system. Lam and Seow (2020) and Jin and Lam (2020) achieved cavity balancing by varying the wall thick ness of the part. A balance filling process within the cavity gives an evenly distributed pressure and tem perature which can drastically reduce the warpage of the part. But the cavity bala ncing is only one of the important influencing factors of part qualities. Espe cially, the part has its functional requirements, and its thicknesses should not be varied usually. From the pointview of the injection mold design, a gate is characterized by its size and location, and the runner system by the size and layout. The gate size and runner layout are usually determined as constants. Relatively, gate locations and runner sizes are more flexible, which can be varied to influence the quality of the part. As a result, they are often the design pa rameters for optimization. Lee and Kim (1996a) optimized the sizes of runners and gates to balance runner system for mul tiple injection cavities. The runner balancing was described as the differences of entrance pressures for a multicavity mold with identical cavities, and as differences of pressures at the 1 end of the melt flow path in each cavity for a family mold with different cavity vo lumes and geometries. The methodology has shown uniform pressure distributions among the cavities during the entire molding cycle of multiple cavities mold. Zhai et al.(2020a) presented the two gate loca tion optimization of one molding cavity by an effi cient search method based on pressure gradient (PGSS), and subsequently positioned weld lines to the desired locations by varying runner sizes for multigate parts (Zhai et al., 2020). As largevolume part, multiple gates are needed to shorten the maxi mum flow path, with a corresponding decrease in injection pressur